No Evidence for Evolution in the Far-Infrared-Radio Correlation out to z ~ 2 in the eCDFS

TL;DR

This study finds no significant evolution in the far-infrared-radio correlation for star-forming galaxies up to redshift 2, suggesting the ratio remains stable over cosmic time despite expectations of change.

Contribution

It provides the first comprehensive analysis of the 70 um FRC out to z > 2 using deep, sensitive data and robust statistical methods, challenging previous assumptions about its evolution.

Findings

FRC remains constant up to z ~ 2

qTIR shows no significant evolution over 0-2 redshift range

Results are consistent across different analysis techniques

Abstract

We investigate the 70 um Far-Infrared Radio Correlation (FRC) of star-forming galaxies in the Extended Chandra Deep Field South (ECDFS) out to z > 2. We use 70 um data from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL), which comprises the most sensitive (~0.8 mJy rms) and extensive far-infrared deep field observations using MIPS on the Spitzer Space Telescope, and 1.4 GHz radio data (~8 uJy/beam rms) from the VLA. In order to quantify the evolution of the FRC we use both survival analysis and stacking techniques which we find give similar results. We also calculate the FRC using total infrared luminosity and rest-frame radio luminosity, qTIR, and find that qTIR is constant (within 0.22) over the redshift range 0 - 2. We see no evidence for evolution in the FRC at 70 um which is surprising given the many factors that are expected to change this ratio at high redshifts.